Correspondence

We describe here the development of a ‘eukaryotic display system ’ for heterologous proteins on the viral and host cell surfaces using Bombyx mori nucleopolyhedrovirus (BmNPV). The reporter gene gfp (green fluorescent protein) was fused to either the gp64 gene encoding the full-length BmNPV envelope protein GP64 or to its 59 region encoding only the N-terminal domain harbouring the signal sequence, and recombinant viruses expressing the corresponding fusion proteins under the strong viral polyhedrin promoter were generated. On infection of the host insect B. mori or the host-derived BmN cells with the full-length GP64–GFP virus, abundant expression of the recombinant protein and its display on the cell surface were achieved. The fusion protein was also a component of the budded virions. Thus, the BmNPV-based display system provides an alternative to the previously established Autographa californica multinucleocapsid nucleopolyhedrovirus display system. The recombinant virus expressing GFP has also been used in preliminary pathological investigations on virus infection in B. mori and provides a simple method for screening for antiviral agents